This invention relates to a process for the preparation of polysiloxanes from halosilanes. More specifically, this invention relates to a process for the preparation of polysiloxanes by reacting halosilanes in the presence of metal oxides and sulfolane.
Polysiloxanes are most commonly prepared by the hydrolysis of halosilanes. One alternative method of preparing polysiloxanes involves the reaction of halosilanes in the presence of metal oxides. Vyle and Kipping in J. Chem. Soc., 2616 (1924) reported that a viscous oil was obtained when diphenyldichlorosilane was reacted with mercuric oxide in a toluene solution. The viscous oil was presumably a polysiloxanes.
Takiguchi et al. in J. Org. Chem., 25, 310(1969) prepared hexaphenylcyclotrisiloxane by the reaction of diphenyldichlorosilane with zinc oxide. Other anhydrous metal oxides, including cupric oxide, lead oxide, silver oxide and manganese dioxide, were found to react in a similar manner.
Frainnet et al. in Bull. Soc. Chim. France, 1480(1960) found that polysiloxanes could be prepared by reacting dimethyldichlorosilane and methylhydrogendichlorosilane with iron (III) oxide.
Andrianov et al. in Zhural Obshchei Khimii, 32, 3951 (1962) reported that dimethyldichlorosilane and iron (III) oxide only react in the presence of a small amount of water or hydrogen chloride.
Shaw et al. in U.S. Pat. No. 2,580,852 (issued Jan. 1, 1952) reported the preparation of polysiloxanes by refluxing a dialkyldichlorosilane with cupric oxide under anhydrous conditions.
Hyde in U.S. Pat. No. 2,571,884 (issued Oct. 16, 1951) prepared linear chlorine endblocked siloxanes by reaction of silicon tetrachloride with a metallic oxide selected from the group MnO.sub.2, CuO, Cu.sub.2 O, CaO, ZnO, MgO, Fe.sub.2 O.sub.3, Ag.sub.2 O, and HgO in the presence of a solvent which contained either nitro groups or nitrile groups.
Hyde in U.S. Pat. No. 2,629,726 (issued Feb. 24, 1953) prepared polysiloxanes by reacting halosilanes with lead oxide, magnesium oxide, calcium oxide, copper oxide, or zinc oxide in the presence of a solvent which contained either nitro groups or nitrile groups.
Pike in U.S. Pat. No. 3,110,720 (issued Nov. 12, 1963) formed cyclic polysiloxanes by reacting dialkyldichlorosilanes with calcium oxide, sodium oxide, potasium oxide, or lithium oxide at a temperature of at least 200.degree. C. in the absence of water or any organic solvent.
It is one object of this present invention to provide a new method for the preparation of polysiloxanes from halosilanes. It is another object to provide a method for the production of polysiloxanes from halosilanes in the absence of water. It is still another object to provide a more efficient process for the production of polysiloxanes from halosilanes in the absence of water. Still other objects will be apparent from a consideration of this specification.